Towing a vehicle with another vehicle occurs frequently. People owning recreation vehicles (RV), for example, often park their RV at an RV park or campground and connect it to any available sources of power and water. If they then want to drive out and explore the region, or run errands, they would have to disconnect their RV and drive it in and out of the campground or park. Typically, the RV owners bring a second vehicle to allow them to come and go without repeatedly disconnecting and reconnecting the RV.
However, towing a vehicle that has its own electrical and signaling system has complications that do not exist when towing something like a trailer. Trailers generally have lights and electrical connections to allow those lights to be selectively powered, such as turn signals and brake lights. Trailers do not provide any power to those lights. The lights are ‘passive’ in that they receive power and control signals from the towing vehicle. Towing a vehicle that has its own electrical system with a source of power and control for the lights becomes far more complicated. Some sort of override or bypass to the towed vehicle's control system is generally needed, while still allowing the towing vehicle to send signals and power to the lights on the towed vehicle.
Several options exist on the market to allow connection of the towed vehicle's electrical system to the towing vehicles electrical system. One of the simpler solutions involves completely bypassing the vehicle's electrical system and using magnetic tow lights. Magnetic tow lights are quick and easy to connect, do not have any interaction with the towed vehicle's system and fits all towed vehicles. However, they are not as secure as one might hope and can present visibility issues on larger vehicles, as they are generally mounted on the top of the vehicle.
Another solution employs a tail light wiring kit. These kits generally include a redundant set of sockets and plugs that mount inside the towed vehicles. While these kits are more secure than the magnetic kits and use the vehicle's own lights, they require enough room in the tail lights for the redundant parts. Some vehicles do not have enough room to allow the installation of the redundant parts.
Another option uses a set of diodes to connect to the towed vehicle's turn signals, running lights and brake signals to that of the towing vehicle. The diodes operate to protect the vehicles' electrical systems. These kits come with large manuals to show how to install them and generally require more advanced knowledge of electrical systems and electronics to allow installation, as well as concerns about damage if installed incorrectly. A risk also exists that the necessary modifications will void any warranties on the vehicle's system.
Yet another solution involves a bulb and socket approach, where the user replaces the sockets inside the lighting assemblies with a different bulb and socket. However, the amount of perceived illumination from a light is closely regulated by the National Highway Traffic Safety Administration. In order to replace the socket, the user typically has to drill an extra hole into the reflector behind the bulbs. This decreases the amount of perceived illumination and may fall below the required standards. Further, the extra hole will allow in moisture that can cause the light to fail completely, or at least to cloud the outer surface, thereby further reducing the perceived illumination.
With the popularity of RVs and the increasing complexity of the electrical systems in cars, having the ability to ‘plug and play’ the wiring harness for towing a vehicle would have several benefits. These include ease of use, ease of installation, and alleviating worries about damage to the electrical system.